02927nas a2200337   4500008004100000245016300041210006900204260000800273300001200281490000700293520190100300653002002201653001602221653002702237653002702264653002802291653001702319653000802336653003002344653001202374653002702386653001702413653002202430653000902452653001502461100002102476700001802497700002002515700002002535856003402555       2000                        eng d00aA comparative analysis of metabolic rate in six Scarabaeus species (Coleoptera : Scarabaeidae) from southern Africa: further caveats when inferring adaptation0 acomparative analysis of metabolic rate in six Scarabaeus species  cApr  a553-5620 v463 aAlterations in VO2 or VCO2 are amongst the more polemical physiological adaptations ascribed to insects. Generally, metabolic rate is thought to be lowered in response to arid conditions, and elevated in species from cold environments compared to their more temperate relatives. However, most studies have rarely addressed the influence of both environmental factors in unison. To this end, standard metabolic rate and its temperature dependence were measured (at 4 degrees C intervals from 16 to 32 degrees C) in six Scarabaeus dung beetle species (three flightless, three volant) from a variety of habitats (warm, arid to cool, mesic) in southern Africa using flow-through respirometry. Mass specific VCO2 varied from 0.0158 mi g(-1) h(-1) at 16 degrees C to 0.1839 ml g(-1) h(-1) at 32 degrees C. The slopes of the rate temperature curves were similar for all species (Q(10)s of 2.14-2.84), although the intercepts differed significantly in the direction (warm arid to cool mesic): S. gariepinus<S. hippocrates<S. striatum<S. galenus<S. rusticus<S. westwoodi. General Linear models were fitted to the VCO2 data with treatment temperature, wing status, mean annual rainfall and mean annual temperature as the independent variables. For all six species, the best fit model included treatment temperature and wing status only. Flightless species had significantly lower VCO(2)s than did winged ones. Amongst the flightless species, S. gariepinus, from the driest area, had the lowest VCO2. Among the winged species it was impossible to determine whether environmental temperature or water availability were most important in influencing VCO2; both were significant. We conclude that investigations of metabolic rate modulation, and especially metabolic cold adaptation, in insects must take both temperature and water availability into account. (C) 2000 Elsevier Science Ltd. All rights reserved.10aacclimatisation10aconsumption10acricket gryllus-firmus10adesiccation resistance10adrosophila-melanogaster10agas-exchange10ains10ametabolic cold adaptation10aoxygen-10arespiratory metabolism10arespirometry10aunselected strain10aVCO210awater-loss1 aDavis, A., L. V.1 aChown, S., L.1 aMcGeoch, M., A.1 aScholtz, C., H.  u<Go to ISI>://00008584250001901783nas a2200193   4500008004100000245011700041210006900158300001000227490000700237520107400244653001801318653002101336653002001357653001601377653001401393100002301407700002201430856013701452       1999                        eng d00aHormonal control of male horn lenght dimorphism in the dung beetle Onthophagus taurus (Coleoptera: Scarabaeidae)0 aHormonal control of male horn lenght dimorphism in the dung beet  a45-530 v453 aMale dung beetles (Onthophagus taurus) facultatively produce a pair of horns that extend from the base of the head: males growing larger than a threshold body size develop long horns, whereas males that do not achieve this size grow only rudimentary horns or no horns at all. Here we characterize the postembryonic development of these beetles, and begin to explore the hormonal regulation of horn growth. Using radioimmune assays to compare the ecdysteroid titers of horned males, hornless males, and females, we identify a small pulse of ecdysteroid which is present in both hornless males and females, but not in horned males. In addition, we identify a brief period near the end of the final (third) larval instar when topical applications of the juvenile hormone analog methoprene can switch the morphology of developing males. Small, normally hornless, males receiving methoprene during this sensitive period were induced to produce horns in 80% of the cases. We summarize this information in two models for the hormonal control of male dimorphism in horn length.10aHorned beetle10aJuvenile hormone10amale dimorphism10aPolyphenism10aThreshold1 aEmlen, Douglas, J.1 aNijhout, Frederik  uhttps://scarabnet.myspecies.info/hormonal-control-male-horn-lenght-dimorphism-dung-beetle-onthophagus-taurus-coleoptera-scarabaeidae01540nas a2200217   4500008004100000245014000041210006900181300001200250490000700262520076100269653001401030653001801044653001601062653001901078653001201097653002101109100001801130700002301148700001301171856013801184       2006                        eng d00aThermoregulation in endothermic dung beetles (Coleoptera: Scarabaeidae): effect of body size and ecophysiological constraints in flight0 aThermoregulation in endothermic dung beetles Coleoptera Scarabae  a854-8600 v523 aWe explore the physiological constraints of body temperature as related to body mass and ambient temperature during flight in endothermic dung beetles showing a mass-related breakpoint where species show strong vs. weak endothermy. We found two different strategies in the dung beetles prior to flight; larger beetles (41.9 g) elevate and maintain their body temperature (Tb) at levels well above ambient temperature (Ta) whereas smaller beetles’ (o1.9 g) Tb tends to conform with Ta. Physiological constraints analysis revealed a constant maximum tolerated temperature (in flight) of 42 1C and a minimum temperature for flight of around 25 1C. These, with body mass, may play a role in thermal niche partitioning and geographical distribution patterns. 10abody size10aEcophysiology10aNull models10aScarabaeoidea.10aScarabs10athermoregulation1 aVerdu, J., R.1 aArellano, Lucrecia1 aNuma, C.  uhttps://scarabnet.myspecies.info/thermoregulation-endothermic-dung-beetles-coleoptera-scarabaeidae-effect-body-size-and-ecophysiologi